Polycarbonate/polylactic acid alloys have drawn attention in terms of reduction of environmental load since polylactic acid is a plant-based resin. Alloying with polylactic acid is effective for increasing the flowability of polycarbonate (optionally abbreviated as PC hereinafter) because of the characteristics of high flowability of polylactic acid, since polycarbonate itself has low flowability.
Also, when polylactic acid is alloyed with polycarbonate and then burned, it is considered to release reduced amount of toxic gases because of its chemical structure, so that it is a promising resin useful in the field of office automation equipment, home appliances, and the like, where flame resisting specification is required.
Conventional PC-polyester alloys are superior in heat resistance and chemical resistance, but poor in flowability, so that alloying with styrene type resins or addition of plasticizers is generally used in order to increase the flowability of PC (for example, refer to Patent document 1). However, attempt to improve the flowability of PC/polyester alloys causes such problem that an ester exchange reaction between resins may lower impact resistance and flame retardancy. PC/poly lactic acid alloys are also similarly low in impact resistance, which has to be improved.
It is generally known that addition of a rubbery elastomer is effective for improving impact resistance of polymer alloys. For example, when a rubbery elastomer with an acrylic structure is added to PC/poly lactic acid alloys, affinity of polylactic acid with the acrylic structure allows dispersion of the rubbery elastomer into polylactic acid to give a resin composition having high impact resistance and high flowability. However, such resin composition is not sufficient in impact resistance at low temperature, hence a resin composition having higher impact resistance at low temperature is requested.
Further, difference in the refractive index between PC and polylactic acid causes defective appearance phenomenon with pearlescence in the PC/poly lactic acid alloy. This defect in appearance makes it difficult to control the glossiness level of pearlescence, which is undesirable in terms of cost because the number of processes in aftertreatment of molded articles, for example, painting and plating processes, are increased.
Patent document 1: Japanese Patent Application Publication No. H7 (1995)-68445